Vitamin C (VITAMIN C (ASCORBIC ACID)) Overview Information

Vitamin C is a vitamin. Some animals can make their own vitamin C, but people must get this vitamin from food and other sources. Good sources of vitamin C are fresh fruits and vegetables, especially citrus fruits. Vitamin C can also be made in a laboratory.

Most experts recommend getting vitamin C from a diet high in fruits and vegetables rather than taking supplements. Fresh-squeezed orange juice or fresh-frozen concentrate is a better pick than ready-to-drink orange juice. The fresh juice contains more active vitamin C. Drink fresh-frozen orange juice within one week after reconstituting it for the most benefit. It you prefer ready-to-drink orange juice, buy it 3 to 4 weeks before the expiration date, and drink it within one week of opening.

Historically, vitamin C was used for preventing and treating scurvy. Scurvy is now relatively rare, but it was once common among sailors, pirates, and others who spent long periods of time onboard ships. When the voyages lasted longer than the supply of fruits and vegetables, the sailors began to suffer from vitamin C deficiency, which led to scurvy.

These days, vitamin C is used most often for preventing and treating the common cold. Some people use it for other infections including gum disease, acne and other skin infections, bronchitis, human immunodeficiency virus (HIV) disease, stomach ulcers caused by bacteria called Helicobacter pylori, tuberculosis, dysentery (an infection of the lower intestine), and skin infections that produce boils (furunculosis). It is also used for infections of the bladder and prostate.

Additional uses include improving physical endurance and slowing aging, as well as counteracting the side effects of cortisone and related drugs, and aiding drug withdrawal in addiction.

Sometimes, people put vitamin C on their skin to protect it against the sun, pollutants, and other environmental hazards. Vitamin C is also applied to the skin to help with damage from radiation therapy.

How does it work?

Vitamin C is required for the proper development and function of many parts of the body. It also plays an important role in maintaining proper immune function.

Age-related vision loss (age-related macular degeneration; AMD). Taking vitamin C in combination with zinc, vitamin E, and beta-carotene daily seems to help prevent vision loss or slow the worsening of AMD in patients with advanced AMD. There is not enough evidence to know if this combination helps people with less advanced macular disease or if it prevents AMD. Using vitamin C with other antioxidants, but without zinc, does not seem to have any effect on AMD.

Decreasing protein in the urine (albuminuria). Taking vitamin C plus vitamin E can reduce protein in the urine in people with diabetes.

Hardening of the arteries (atherosclerosis). Taking vitamin C by mouth seems to decrease the risk of artery hardening. Vitamin C also appears to slow the rate at which artery hardening worsens. More research is needed to understand the effects of vitamin C intake from the diet or supplements on this condition once it has developed.

Cancer. Consuming vitamin C in the diet might decrease the risk of developing mouth cancers and other cancers. Some research suggests that increasing vitamin C intake through fruits and vegetables reduces the risk of cancer. However, taking vitamin C supplements does not appear to reduce cancer risk.

Common cold. There is some controversy about the effectiveness of vitamin C for treating the common cold. However, the majority of evidence shows that taking high doses of vitamin C might shorten the course of the cold by 1 to 1.5 days in some patients. Taking vitamin C is not effective for preventing the common cold.

Kidney problems related to contrast media used during a diagnostic test called angiography. Taking vitamin C before and after an angiography seems to reduce the risk of developing kidney problems.

Redness (erythema) after cosmetic skin procedures. There is some evidence that using a particular vitamin C skin cream can decrease the amount and duration of skin redness following laser resurfacing for scar and wrinkle removal.

High blood pressure. Taking vitamin C along with conventional blood pressure-lowering medications appears to decrease systolic blood pressure (the top number in a blood pressure reading) by a small amount, but does not seem to decrease diastolic pressure (the bottom number). Taking vitamin C supplements alone does not seem to affect blood pressure.

Lead poisoning. Consuming vitamin C in the diet seems to lower blood levels of lead.

Helping medicines used for chest pain work longer. Taking vitamin C by mouth seems to help medicines used for chest pain, such as nitroglycerine, work longer.

Osteoarthritis. Taking vitamin C from dietary sources or from calcium ascorbate supplements seems to prevent cartilage loss and worsening of symptoms in people with osteoarthritis.

Bronchitis. Taking vitamin C by mouth does not seem to have any effect on bronchitis.

Alzheimer's disease and dementia. Vitamin C, consumed as part of the diet, as a supplement, or together with vitamin E, does not seem to reduce the risk of developing Alzheimer’s disease or dementia. However, some research suggests that high, long-term use of vitamin C and E supplements is associated with a reduced risk of Alzheimer’s disease.

Eye disease associated with a medicine called interferon. Taking vitamin C daily by mouth does not seem to reduce the risk of eye disease associated with interferon therapy in people with liver disease.

Lung cancer. Research suggests that taking vitamin C, alone or together with vitamin C, does not reduce the risk of lung cancer or death due to lung cancer.

Death from any cause. Some research suggests that high vitamin C blood levels are associated with a lower risk of death from any cause. However, other research shows that taking vitamin C daily together with vitamin E, beta-carotene, selenium, and zinc does not lower the risk of death. Overall, most research suggests that vitamin C supplements do not reduce the risk of death.

Pancreatic cancer. Research shows that taking vitamin C together with beta-carotene plus vitamin E does not reduce the risk of pancreatic cancer.

High blood pressure during pregnancy (pre-eclampsia). Some research suggests that taking vitamin C by mouth along with vitamin E seems to prevent high blood pressure during high-risk pregnancies. However, most research shows that taking vitamin C with vitamin E does not reduce the risk of high blood pressure during pregnancy.

Complications during pregnancy. Research suggests that taking vitamin C, alone or with vitamin E, does not reduce the risk of complications during pregnancy.

Prostate cancer. Research shows that taking a combination of vitamin C, vitamin E, beta-carotene, selenium, and zinc does not reduce the risk of prostate cancer. Overall, most evidence suggests that taking vitamin C supplements does not reduce the risk of developing prostate cancer.

Hay fever (Allergic rhinitis). There is conflicting evidence about the effects of vitamin C for improving symptoms of hay fever. Taking vitamin C does not seem to prevent hay fever.

Damage to heart caused by the cancer drug anthracycline. Research suggests that taking vitamin C, along with vitamin E and other ingredients, does not reduce the risk of heart damage caused by the cancer drug anthracycline.

Asthma. There is some evidence that people with asthma might have low vitamin C levels. However, research suggests that taking vitamin C does not reduce the risk of developing asthma or improve asthma symptoms.

Attention deficit-hyperactivity disorder (ADHD). Some evidence suggests that taking high doses of vitamin C does not reduce ADHD symptoms. Other research suggests that taking lower doses of vitamin C might improve some symptoms such as restlessness and self-control in children with ADHD.

Autism. Early evidence suggests that taking vitamin C reduces the severity of autism symptoms in children.

Breast cancer. Research on the effects of vitamin C for treating breast cancer conflicts. Some research suggests that high vitamin C intake in the diet reduces breast cancer risk, while other research suggests it has no effect. There is no evidence that taking vitamin C supplements reduces the risk of developing breast cancer.

Burns. Early evidence suggests that using a vitamin C infusion within the first 24 hours of severe burns reduces wound swelling.

Heart disease. Research on the use of vitamin C for heart disease is unclear. More research on the use of vitamin C supplements for preventing heart disease is needed. However, increasing vitamin C intake in the diet might provide some benefit.

Cataracts. There is conflicting information about the use of vitamin C to prevent cataracts. Vitamin C plus vitamin E and beta-carotene does not seem to have any significant effect on age-related loss of vision due to cataracts in well-nourished people who take the supplement long-term (for an average of 6.3 years). On the other hand, other research suggests that taking multivitamins that contain vitamin C for 10 years seems to prevent cataracts. Use of supplements for shorter periods does not appear to work.

Cervical cancer. Some limited research suggests that taking vitamin C reduces the risk of cervical cancer.

Damage to the colon due to radiation exposure (chronic radiation proctitis). Early research suggests that taking vitamin C plus vitamin E might improve some symptoms of chronic radiation proctitis.

Colorectal cancer. Taking vitamin C together with vitamin E and beta-carotene does not seem to reduce the risk of colorectal cancer. Vitamin C intake from the diet also does not appear to be linked to colorectal cancer risk.

Diabetes. Some research suggests that taking vitamin C decreases blood sugar and cholesterol levels in people with diabetes. However, other research suggests that vitamin C does not improve blood sugar in people with diabetes. Vitamin C does not appear to decrease the risk of developing diabetes.

Endometrial cancer. Research suggests that vitamin C intake from the diet slightly lowers the risk of endometrial cancer.

Esophageal cancer. Taking vitamin C along with beta-carotene plus vitamin E does not reduce the risk of developing esophageal cancer. However, higher vitamin C intake in the diet appears to be linked to a lower risk of esophageal cancer.

Stomach cancer. Not all research agrees on whether or not taking vitamin C supplements or getting extra vitamin C in the diet can prevent stomach cancer. Taking vitamin C supplements in combination with beta-carotene or beta-carotene plus vitamin E does not seem to reduce the risk of stomach cancer. However, some evidence suggests that taking vitamin C alone might keep precancerous sores in the stomach from progressing to cancer in people at high risk for stomach cancer.

Gout. Research shows that increased vitamin C intake from the diet is linked to a lower risk of gout in men.

HIV/AIDS. Taking vitamin C daily together with vitamin A, beta-carotene, vitamin E, selenium, and coenzyme Q-10 seems to have some benefits for people with HIV/AIDS. However, neither high nor low doses of vitamin C affect how much of the virus is active in the body.

HIV transmission. Taking vitamin C along with vitamin B and vitamin E during pregnancy and breast-feeding seems to reduce the risk of transmitting HIV to the infant.

High cholesterol. Taking vitamin C daily does not seem to lower cholesterol in people with normal cholesterol levels. However, research suggests that taking vitamin C reduces low-density lipoprotein (LDL or “bad”) cholesterol in people with high cholesterol.

Infertility. There is early evidence that women with certain fertility problems might benefit from taking vitamin C daily.

Leukemia. There is some evidence that vitamin C might enhance the effects of the drug arsenic trioxide (Trisenox) in people with leukemia.

Liver disease (nonalcoholic steatohepatitis). Early research suggests that taking vitamin C together with vitamin E might improve some aspects of liver function in people with a certain liver disease called nonalcoholic steatohepatitis. However, it does not seem to decrease liver swelling in people with this condition.

Osteoporosis. Some evidence suggests that vitamin C might improve bone strength. However, higher vitamin C blood levels in postmenopausal women have been linked to lower bone mineral densities. More information is needed on the effects of vitamin C on bone mineral density.

Ovarian cancer. Consuming vitamin C in the diet does not seem to affect the risk of developing ovarian cancer.

Parkinson’s disease. Research suggests that increased vitamin C intake in the diet does not reduce the risk of Parkinson’s disease.

Pneumonia. Some research suggests that vitamin C might reduce the risk of pneumonia, as well as the duration of pneumonia once it develops.

Bed sores (pressure ulcers). Some evidence suggests that taking vitamin C does not improve wound healing in people with pressure ulcers. However, other research suggests that taking vitamin C reduces the size of pressure ulcers.

Vitamin C (VITAMIN C (ASCORBIC ACID)) Side Effects & Safety

Vitamin C is LIKELY SAFE for most people when taken by mouth in recommended doses, when applied to the skin, when injected into the muscle, and when injected intravenously (by IV) and appropriately. In some people, vitamin C might cause nausea, vomiting, heartburn, stomach cramps, headache, and other side effects. The chance of getting these side effects increases the more vitamin C you take. Amounts higher than 2000 mg daily are POSSIBLY UNSAFE and may cause a lot of side effects, including kidney stones and severe diarrhea. In people who have had a kidney stone, amounts greater than 1000 mg daily greatly increase the risk of kidney stone recurrence.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Vitamin C is LIKELY SAFE for pregnant or breast-feeding women when taken by mouth in amounts no greater than 2000 mg daily for women over 19 years-old, and 1800 mg daily for women 14 to 18 years-old, or when given intravenously (by IV) or intramuscularly and appropriately. Taking too much vitamin C during pregnancy can cause problems for the newborn baby. Vitamin C is POSSIBLY UNSAFE when taken by mouth in excessive amounts.

Infants and children: Vitamin C is LIKELY SAFE when taken by mouth appropriately. Vitamin C is POSSIBLY UNSAFE when taken by mouth in amounts higher than 400 mg daily for children 1 to 3 years, 650 mg daily for children 4 to 8 years, 1200 mg daily for children 9 to 13 years, and 1800 mg daily for adolescents 14 to 18 years.

Angioplasty, a heart procedure: Avoid taking supplements containing vitamin C or other antioxidant vitamins (beta-carotene, vitamin E) immediately before and following angioplasty without the supervision of a health care professional. These vitamins seem to interfere with proper healing.

Cancer: Cancerous cells collect high concentrations of vitamin C. Until more is known, only use high doses of vitamin C under the direction of your oncologist.

Diabetes: Vitamin C might raise blood sugar. In older women with diabetes, vitamin C in amounts greater than 300 mg per day increases the risk of death from heart disease. Do not take vitamin C in doses greater than those found in basic multivitamins.

Blood-iron disorders, including conditions called “thalassemia” and “hemochromatosis”: Vitamin C can increase iron absorption, which might make these conditions worse. Avoid large amounts of vitamin C.

Kidney stones, or a history of kidney stones: Large amounts of vitamin C can increase the chance of getting kidney stones. Do not take vitamin C in amounts greater than those found in basic multivitamins.

Heart attack: Vitamin C levels are reduced during a heart attack. However, low vitamin C has not been linked to an increased risk for heart attack.

A metabolic deficiency called “glucose-6-phosphate dehydrogenase” (G6PD) deficiency: Large amounts of vitamin C can cause red blood cells to break in people with this condition. Avoid excessive amounts of vitamin C.

Smoking and chewing tobacco: Smoking and chewing tobacco lowers vitamin C levels. Vitamin C intake in the diet should be increased in people who smoke or chew tobacco.

Vitamin C (VITAMIN C (ASCORBIC ACID)) Interactions

Aluminum is found in most antacids. Vitamin C can increase how much aluminum the body absorbs. But it isn't clear if this interaction is a big concern. Take vitamin C two hours before or four hours after antacids.

Estrogens interacts with VITAMIN C (ASCORBIC ACID)

The body breaks down estrogens to get rid of them. Vitamin C might decrease how quickly the body gets rid of estrogens. Taking vitamin C along with estrogens might increase the effects and side effects of estrogens.

Fluphenazine (Prolixin) interacts with VITAMIN C (ASCORBIC ACID)

Large amounts of vitamin C might decrease how much fluphenazine (Prolixin) is in the body. Taking vitamin C along with fluphenazine (Prolixin) might decrease the effectiveness of fluphenazine (Prolixin).

Taking large doses of vitamin C might reduce how much of some medications used for HIV/AIDS stays in the body. This could decrease the effectiveness of some medications used for HIV/AIDS.
Some of these medications used for HIV/AIDS include amprenavir (Agenerase), nelfinavir (Viracept), ritonavir (Norvir), and saquinavir (Fortovase, Invirase).

Taking vitamin C, beta-carotene, selenium, and vitamin E together might decrease the effectiveness of some medications used for lowering cholesterol. It is not known if vitamin C alone decreases the effectiveness of some medications used for lowering cholesterol.
Some medications used for lowering cholesterol include atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), and pravastatin (Pravachol).

Niacin interacts with VITAMIN C (ASCORBIC ACID)

Taking vitamin C along with vitamin E, beta-carotene, and selenium might decrease some of the helpful effects of niacin. Niacin can increase the good cholesterol. Taking vitamin C along with these other vitamins might decrease the effectiveness of niacin for increasing good cholesterol.

Warfarin (Coumadin) interacts with VITAMIN C (ASCORBIC ACID)

Warfarin (Coumadin) is used to slow blood clotting. Large amounts of vitamin C might decrease the effectiveness of warfarin (Coumadin). Decreasing the effectiveness of warfarin (Coumadin) might increase the risk of clotting. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

The body breaks down acetaminophen (Tylenol, others) to get rid of it. Large amounts of vitamin C can decrease how quickly the body breaks down acetaminophen. It is not clear exactly when or if this interaction is a big concern.

Aspirin interacts with VITAMIN C (ASCORBIC ACID)

The body breaks down aspirin to get rid of it. Large amounts of vitamin C might decrease the breakdown of aspirin. Decreasing the breakdown of aspirin might increase the effects and side effects of aspirin. Do not take large amounts of vitamin C if you take large amounts of aspirin.

Vitamin C might decrease how quickly the body gets rid of choline magnesium trisalicylate (Trilisate). But it is not clear if this interaction is a big concern.

Nicardipine (Cardene) interacts with VITAMIN C (ASCORBIC ACID)

Vitamin C is taken up by cells. Taking nicardipine (Cardene) along with vitamin C might decrease how much vitamin C is taken in by cells. The significance of this interaction is not clear.

Nifedipine interacts with VITAMIN C (ASCORBIC ACID)

Vitamin C is taken up by cells. Taking nifedipine (Adalat, Procardia) along with vitamin C might decrease how much vitamin C is taken in by cells. The significance of this interaction is not clear.

Salsalate (Disalcid) interacts with VITAMIN C (ASCORBIC ACID)

Vitamin C might decrease how quickly the body gets rid of salsalate (Disalcid). Taking vitamin C along with salsalate (Disalcid) might cause too much salsalate (Disalcid) in the body, and increase the effects and side effects of salsalate.

Vitamin C (VITAMIN C (ASCORBIC ACID)) Dosing

The following doses have been studied in scientific research:

BY MOUTH:

For scurvy: 100-250 mg once or twice daily for several days.

For treating the common cold: 1-3 grams daily.

For preventing kidney damage related to contrast media used during diagnostic tests: vitamin C 3 grams is given before coronary angiography and then 2 grams is given after the procedure in the evening and again the following morning.

For slowing progression of hardening of the arteries: slow-release vitamin C 250 mg in combination with 91 mg (136 IU) of vitamin E twice daily for up to 6 years.

For tyrosinemia in premature infants on high protein diets: 100 mg of vitamin C.

The daily recommended dietary allowances (RDAs) are: Infants 0 to 12 months, human milk content (older recommendations specified 30-35 mg); Children 1 to 3 years, 15 mg; Children 4 to 8 years, 25 mg; Children 9 to 13 years, 45 mg; Adolescents 14 to 18 years, 75 mg for boys and 65 mg for girls; Adults age 19 and greater, 90 mg for men and 75 mg for women; Pregnancy and Lactation: age 18 or younger, 115 mg; ages 19 to 50 years 120 mg. People who use tobacco should take an additional 35 mg per day.
Do not take more than the following amounts of vitamin C: 400 mg per day for children ages 1 to 3 years, 650 mg per day for children 4 to 8 years, 1200 mg per day for children 9 to 13 years, and 1800 mg per day for adolescents and pregnant and breast-feeding women 14 to 18 years, and 2000 mg per day for adults and pregnant and lactating women.

APPLIED TO THE SKIN:

Most topical preparations used for aged or wrinkled skin are applied daily. Studies have used creams containing 5% to 10% vitamin C. In one study a specific vitamin C formulation (Cellex-C High Potency Serum) used 3 drops applied daily to areas of facial skin. Don’t apply vitamin C preparations to the eye or eyelids. Also avoid contact with hair or clothes. It can cause discoloration.

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